Library Functions Manual
NAME getloadavg — get system load averages
LIBRARY Standard C Library (libc, -lc)
SYNOPSIS #include <stdlib.h>
getloadavg(double loadavg, int nelem);
DESCRIPTION The getloadavg() function returns the number of processes in the system run queue averaged over various periods of time. Up to nelem samples are retrieved and assigned to successive elements of loadavg. The system imposes a maximum of 3 samples, representing averages over the last 1, 5, and 15 minutes, respectively.
RETURN VALUES If the load average was unobtainable, -1 is returned; otherwise, the number of samples actually retrieved is returned.
HISTORY The getloadavg() function appeared in 4.3BSD-Reno.